Teenage mutant ninja turtles are said to have been behind the fad of terrapins as pets [P/H]

The reptiles originate in eastern North America. Their eggs need sustained warm weather to hatch, with incubation taking 120 days in temperatures around 27C (80F).

As well as biting any passing human, they also wolf down ducklings and frogs and feast on fish like roach, carp and bream.

Canal and River Trust ecologist Paul Wilkinson said: "It could be bad news for conservation because they are not a native species - they come from the eastern states of North America, such as the swamps of Florida.

"We've been concerned that the trend of increasing temperatures associated with climate change would give terrapins the conditions they need to successfully breed, something which could be a disaster for some native wildlife."

A five day heatwave with temperatures reaching 81F is set to begin this weekend [BNPS]

His warning echoes that of Wetheriggs Animal Rescue and Conservation Centre in Cumbria, who last summer recovered 14 terrapins from the rivers Eden and Eamont.

Centre director Terry Bowes said: "The problem is both the number being dumped, as well as the way they devastate the wildlife. They are carnivores. They will eat anything that moves.

"We have two snapping turtles as well as the terrapins, and they could very easily take the finger off a small child. They can become quite aggressive when they have grown."

Wall-to-wall sunshine is predicted from tomorrow for at least five days with temperatures expected to reach 81F by Tuesday.